Track-mounted drilling machines include a frame supported by two tracks (also known as crawlers) for movement over the ground (also known as tramming). Typical drilling machines include an operator cab, a tower, a rotary head and a drill string. The operator cab and tower are mounted on the frame, with the tower pivotable with respect to the frame such that the tower can be lowered into a horizontal position for transport and raised to a generally vertical position for drilling. The rotary head is mounted to the tower, is connected to the drill string, and is operable to rotate the drill string and force the drill string downward to penetrate the ground at a desired angle and create a drilled hole.
With prior art drilling machines, prior to drilling a hole, it is necessary to level the frame and then pivot the tower to a desired vertical position with respect to the frame in order to ensure that the drill string penetrates the ground at a desired orientation with respect to gravity. Typically the leveling is accomplished using jacks once the drilling machine has been moved to its desired drilling position.
Additionally, most prior art drilling machines include at best passive, non-independent suspension systems that only partially absorb ground forces resulting from movement over uneven surface terrain, often resulting in a bumpy ride for the operator. For example, some prior art machines include a rigid connection between the tracks and the frame only allowing a rotation motion of the tracks with respect to the frame. Such a rigid connection significantly limits the maximum tramming speed of the drilling machine.